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Ecoregion Description


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Species Richness


# of Endemic Species


Threats

151: Cumberland

Major Habitat Type:

temperate upland rivers

Author:

Text modified from Abell et al. 2000. Freshwater Ecoregions of North America: A Conservation Assessment. Island Press, Washington, DC, USA

Countries:

United States

Boundaries:

The ecoregion is defined by the watershed of the Cumberland River, which drains to the larger Mississippi Basin. The ecoregion borders Tennessee and Kentucky, covering much of southern Kentucky and north-central Tennessee.

Drainages flowing into:

The Cumberland River drains to the larger Mississippi Basin by way of the Ohio River.

Main rivers or other water bodies:

In the northern portion of the ecoregion, the mainstem Cumberland River originates at the confluence of the Poor and Clover forks; in total, the Cumberland drains more than 46,000 km2 before joining the Ohio River at Smithland, Kentucky (Ono et al. 1983). Tributaries to the Cumberland include the Big South Fork, Rockcastle, and Little rivers. 

Although the Tennessee and Cumberland rivers flow quite close to each other near their confluence with the Ohio, they were not physically linked historically. Today, dam construction on both rivers has changed this situation. The construction of Barkley Dam impounded the Cumberland, forming Lake Barkley, while just a few miles away the Kentucky Dam was built to impound the Tennessee River, thereby creating Kentucky Lake. This alone was not enough to link the two reservoirs, so a channel was cut not far from the head of each lake to link them together. Other mainstem and tributary reservoirs constructed by the Tennessee Valley Authority for flood storage and power generation are also major surface water features.

Topography:

The topography of the ecoregion is diverse, with valleys, ridges, and falls downcut by major streams. Topographical features include the Highland Rim, a crater rising 250 – 300 m that encircles the Nashville basin. It is characterized by deep channels incised by the lower Cumberland River. Rising 300- 900 m altitude in the east lies the Cumberland Plateau, which consists of sandstones, shales and coals. Here, falls have formed over resistant sandstone substrates, with Cumberland Falls being the most notable (Starnes & Etnier 1986).

Climate:

The ecoregion lies along the northern edge of the humid subtropical climate zone in North America (Köppen 1936). Precipitation averages around 1200 mm, with the summer months being the wettest. Temperatures average 13 oC (McNab & Avers 1994).

Freshwater habitats:

The region’s physiographic and geological diversity accounts for much of the faunal diversity of the ecoregion. The Highland Rim is characterized by numerous caves, springs, surface streams, falls, and a labyrinth of subterranean channels. Streambeds of the Nashville basin are typically low gradient, meandering, and highly productive. Except for the headwaters of the Cumberland, which drain the steep slopes of the Cumberland Mountains, streams of the Cumberland Plateau are generally incised, meandering, with low productivity (Starnes & Etnier 1986).

Terrestrial Habitats:

The western half of the ecoregion is characterized by deciduous broadleaf forests, dominated by oak-hickory communities. Appalachian mixed mesophytic forests are the dominant communities on the eastern side of the ecoregion. These relict stands were once widespread across temperate North America, and served as mesic refuges during drier glacial periods (Ricketts et al. 1999).

Fish Fauna:

The Tennessee and Cumberland ecoregions together contain the highest level of freshwater diversity in North America and are possibly the most diverse temperate freshwater ecoregions in the world (Starnes 1986; Olson and Dinerstein 1998). In fish, mussel, and crayfish species, the region is the most species-rich and has the highest number of endemics in North America. This high diversity is derived largely from the range of habitat types represented in the ecoregions, as well as their location adjacent to Atlantic Slope, eastern Gulf Slope, lower Mississippi River, and Ohio River drainages, all with distinctive faunas (Starnes 1986).

Although not as rich as the Tennessee drainage [152], the Cumberland ecoregion harbors a large diversity of freshwater taxa. Stream capture, the process by which the headwaters of a drainage basin are naturally diverted to a neighboring one, has affected distributional patterns between the Cumberland and Green rivers and between the Cumberland and Tennessee rivers (Starnes & Etnier 1986).

Description of endemic fishes:

Species endemic to the ecoregion include a couple of darters (Etheostoma forbesi and E. luteovinctum), two shiners (Notropis albizonatus and N. rupestris), blotched chub (Erimystax insignis), barrens topminnow (Fundulus julisia) and the blackside dace (Phoxinus cumberlandensis), which is restricted to the upper Cumberland drainage above Big South Fork (Starnes & Etnier 1986).

Other noteworthy aquatic biotic elements:

The Tennessee [152] and Cumberland ecoregions contain globally high richness and endemism in mussels, crayfish, and other invertebrates.

Justification for delineation:

Ecoregion boundaries are modified from Abell et al. (2000), which based its units on subregions defined by Maxwell et al. (1995). Modifications to this ecoregion were made following recommendations from the Endangered Species Committee of the American Fisheries Society. Based on faunal data from Hocutt & Wiley (1986), the Endangered Species Committee decided there was a significant number of species exclusively endemic to the Cumberland [151] and Tennessee [152] drainages to warrant separate ecoregions. 

References/sources:

Abell, R. A., Olson, D. M., et al. (2000). "Freshwater Ecoregions of North America: A Conservation Assessment" Washington, DC, USA: Island Press.

Hocutt, C. H.,Wiley, E. O. (Ed.) (1986). "The zoogeography of North American freshwater fishes" New York, USA: John Wiley & Sons.

Maxwell, J. R., Edwards, C. J., et al. (1995) "A hierarchical framework of aquatic ecological units in North America (Nearctic Zone)". St. Paul, MN. North Central Forest Experiment Station, USDA Forest Service.

McNab, W. H.,Avers, P. E. (1994) "Ecological subregions of the United States". U.S. Forest Service, ECOMAP Team, WO-WSA-5. Online. http://www.fs.fed.us/land/pubs/ecoregions/index.html..

Olson, D. M.,Dinerstein, E. (1998). "The global 200: A representation approach to conserving the Earth's most biologically valuable ecoregions" Conservation Biology 12(3) 502-515.

Ono, R. D., Williams, J. D., et al. (1983). "Vanishing fishes of North America" Washington, DC, USA: Stone Wall Press, Inc..

Starnes, W. C.,Etnier, D. A. (1986)"Drainage evolution and fish biogeography of the Tennessee and Cumberland rivers drainage realm" In Hocutt, C.H.;Wiley, E.O. (Ed.). The zoogeography of North American freshwater fishes. (pp. 325-361) New York, New York, USA: Wiley.

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